package com.study;

import java.util.ArrayList;
import java.util.Collections;
import java.util.List;

/**
 * @author MI
 * @version 1.0
 * @date 2021/4/19 17:14
 */
public class Demo {
    public static void main(String[] args) {
        String s = null;
        System.out.println(s);
        //线程不安全
        StringBuilder stringBuilder = new StringBuilder();
        //线程安全
        StringBuffer stringBuffer = new StringBuffer();

        final List<String> objects = Collections.synchronizedList(new ArrayList<>());
    }
}
